Systematic Phenotyping and Characterization of the 5xFAD mouse model of Alzheimer’s Disease

Abstract

Mouse models of human diseases are invaluable tools for studying pathogenic mechanisms and testing interventions and therapeutics. For disorders such as Alzheimer's disease in which numerous models are being generated, a challenging first step is to identify the most appropriate model and age to effectively evaluate new therapeutic approaches. Here we conducted a detailed phenotypic characterization of the 5xFAD model on a congenic C57BL/6J strain background, across its lifespan, including a seldomly analyzed 18-month old time point to provide temporally correlated phenotyping of this model and a template for characterization of new models of LOAD as they are generated. This comprehensive analysis included quantification of plaque burden, β biochemical levels, and neuropathology, neurophysiological measurements and behavioral and cognitive assessments, and evaluation of microglia, astrocytes, and neurons. Analysis of transcriptional changes was conducted using bulk-tissue generated RNA-seq data from microdissected cortices and hippocampi as a function of aging, which can be explored at the UCI Mouse Explorer and AD Knowledge Portal. This deep-phenotyping pipeline identified novel aspects of age-related pathology in the 5xFAD model.

Single-cell and nucleus RNA-seq in a mouse model of AD reveal activation of distinct glial subpopulations in the presence of plaques and tangles

“…The overexpression of Thy1 in our data could be due to greater expression of the transgene in both models. Astrocytes expressing Thy1 were substantially enriched in the 5xFAD mice, which are known to have increased number of astrocytes 6 , compared to the 3xTg-AD. Thus, Thy1 might serve as an additional marker of astrocyte activation.…”

“…For bulk RNAseq the animals were sacrificed via CO2 inhalation and transcardially perfused with 1X phosphate buffered saline (PBS). For single-cell experiments, animals were sacrificed and perfused as previously described 6 . Half of the brain was kept in a Hank's balanced salt solution (HBSS) without Calcium and Magnesium and used fresh for single-cell experiments while the other half was snap frozen and stored for single-nucleus isolation.…”

“…The modules obtained from WGCNA analysis in 3xTg-AD samples were compared to previously identified 5xFAD modules 6 and to human AMP-AD modules 42 by calculating genes overlap and significance (p-value) as previously described 6 . Briefly, the gene overlap…”

“…We analyzed a bulk RNA-seq time course of 3xTg-AD hippocampus at 4, 12, and 18 months of age to understand the transcriptional changes that occur during aging in this model. Female 3xTg-AD (as well as female 5xFAD) mice have shown increased pathology when compared to males, likely due to the Thy1 mini-gene, which regulates the expression of the cDNAs in the transgenes 6 . Therefore, we expected stronger upregulation of ADassociated genes in females.…”

“…One extensively characterized model is the 5xFAD mouse that develops an aggressive plaque pathology marked by early amyloid peptide accumulation at around 2 months of age (the equivalent of an 18-year-old human) but no tangles 5,6 . Thus, 5xFAD is a valuable model for amyloidosis but does not fully recapitulate AD.…”